The following terminology is used in this application: a data packet is a data unit of variable size; a header is a part of a data packet containing information about the data packet, for example it's type, source address and destination address; the body part or payload is the part of the data packet containing data transmitted via the packet; a datagram is a data packet containing by itself all information needed to transmit the packet to its destination; so the network used for transmitting does not need to be configured before sending the packets; a connectionless network is a network in which data can be sent without setting up a connection in advance; a router device is a network node connected to two or more networks that may be of the same type or may be of different types, said router device in use forwarding data packets from one network to another.
In communication or computer networks transmission bandwidth is limited; for example a telephone line, as generally used to connect users to the Internet, has a transport capacity of only 28.8 kilobytes per second. A large part of the occupied bandwidth is used in an inefficient manner, because a significant part of the transmitted data packets is not data, but merely information required by transport protocols about the packet itself, for example information on the data packet type or the source and destination address of the packet. It is known that about 38.9% of the packets transmitted via the Internet has a total length of 40 bytes. These packets are in accordance with the Internet Protocol version 4 (IPv4) and since the IPv4 protocol requires 20 bytes of information about the packet, only 50% of the occupied bandwidth is used for payload.